Eocene–Oligocene extinction event. Millions of years ago Eocene–Oligocene extinction is labeled E– OG.
The 33.9 Ma transition between the end of the Eocene and the beginning of the Oligocene, called the Grande Coupure (the "Great Break" in continuity) in Europe, is marked by large-scale extinction and floral and faunal turnover (although minor in comparison to the largest mass extinctions).
Lutetian age. Bartonian age. Priabonian age. Mammal. Eocene. The Eocene /ˈiːəsiːn/ (symbol Eo [2]) epoch, lasting from 56 to 33.9 million years ago, is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era.
The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C. The end is set at a major extinction event called the Grande Coupure (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay.